This invention relates to a packaged heat generator usually known as a body warmer which provides thermal energy by mixing two compositions of metallic powders and oxidation promotors and by exposing the mixtures to air or oxygen in the air.
There is known a prior art by which heat is provided by mixing two or more kinds of elements including metallic powders such as iron powders and oxidation promotors such as humidified activated charcoal powders, and by exposing the mixtures to air. Conventional body warmers or pocket heaters usually in use during the winter days, and other conventional heaters in therapeutic or medical use incorporate the above art. However, those heaters are given little or no consideration of the amount of thermal energy or duration of heating that the heaters should provide, and therefore, they are not satisfactory from its practical standpoint. In other words, the conventional heaters have several problems yet to be solved. First, unless provision is made to prevent the surface oxidation of the metallic powders, the surface oxidation will persist through the period during which they remain not in use or sealed, and at the time the heaters are actually used, they will have lost considerable amounts of heating potential, and last only for a very short period of time. Secondly, if the mixtures are only made to be exposed to air, they will be unable to provide the different temperatures of heating desired depending on the different situation in which they are used. Thirdly, once they are made to begin heating, the heating cannot be interrupted at any desired time, but must continue until it is finally exhausted.